DESCRIPTION: Matrix-assisted laser desorption/ionization (MALDI) coupled to mass spectrometry has emerged in recent years as a powerful new resource for the biomedical researcher. Applications to the analysis of a wide range of important classes of biomolecules, including proteins, peptides, monoclonal antibodies, oligonucleotides and glycoproteins have been particularly impressive. Basic Studies of the fundamental mechanism involved in MALDI are still required to improved the basic understanding of the desorption process itself. These studies are expected to expand the applicability of the technique and provide improvements in such areas as molecular mass accuracy, sensitivity and mass resolution for biologically relevant materials. Recent results based upon the continually evolving models of the desorption/ionization process have expanded its utility beyond simple molecular weight determinations. Metastable ion decay products produced in MALDI are very useful in providing sequence information for peptides and some proteins. Advantages over conventional approaches include the speed of analysis and high sensitivity (picomoles) of the method. Such capabilities offer new opportunities for the biochemical researcher. A variety of basic studies are proposed to improve both the fundamental understanding of the metastable ion decay process and explore the analytical utility of the sequence ions produced from peptides and proteins. Improvements to existing instrumentation are proposed to allow a systematic study of the experimental parameters affecting both the short and long term metastable decay process important in time-of-flight mass spectrometry (TOF-MS). Such studies might also assist in the utility of the MALDI TOF-MS technique for more facile biochemical systems such as larger oligonucleotides. Metastable decay process appear to be a limiting factor in the mass resolution which can be obtained for larger oligonucleotides. Extension of the MALDI technique to include mid-infrared laser desorption (2.8 mu m) is proposed which may allow more biologically compatible matrices to be utilized (frozen buffered aqueous solutions). This approach may allow noncovalent molecular interactions (tertiary structures) to survive the MALDI process. This would open up a wide range of important biological systems for study by mass spectrometry. In addition, basic factors important to the ionization process will be explored that could lead to new application areas for this technique and to improvements in existing methodology.